Substitute
by Channel D
Summary: When a lab injury sidelines Abby, Tim is appointed to fill in for her because Gibbs suspects the accident was Tim's fault. Tim knows he's no Abby! One-shot, written for the NFA Hors de Combat challenge.


**Substitute**

**by channeld**

_written for_: the NFA _Hors de Combat_ challenge. The goal of the challenge is to write about what happens when an injury takes a teammate out of action.  
_rating_: K plus  
_genre_: drama  
_characters_: Tim, Gibbs, Tony, Ziva

* * *

_disclaimer_: I still own nothing of NCIS.

* * *

Tim stood just inside the door of Abby's lab…rather, the space where the door once had been. He and Gibbs stepped in a little further, and to one side, as workmen came up to the space with sheets of plywood to nail in place, once they had knocked out the remaining bits of glass. "Uh, boss; are you sure that the lab is, uh, okay to work in?"

Gibbs barely gave a glance to the freshly washed-down surfaces and to the damaged equipment that had been pushed to one side. "It'll do. You got a problem with that, McGee?"

"Ah, no, boss. But, uh…why are you showing me this?"

With a glare that would crack ice, Gibbs said, "Because this is going to be your home for the next couple of weeks, until Abby has recovered and is back at work. _You _did something to blow this place up; _you _can take her place."

Tim's three cracked, taped ribs ached all the more as his heart pounded. "But boss, I don't think I _did _anything. The last thing I remember was waking up in the ambulance, and…"

"I don't buy that. Abby's not one to make a mistake that would cause her lab to blow up. You were the only one with her at the time. Therefore, _you_ did it."

What Gibbs said did make some sense, and yet…Tim couldn't remember doing anything at all that might have caused yesterday's explosion. Now Abby was in the hospital, recovering from surgery. Tim had gotten off lightly. He could have taken time off work, but he didn't want to seem like a wuss in comparison to Abby's graver injuries. He'd figured that he would be on desk duty for a few weeks, until his doctor cleared him to return to the field, but… "Boss, I honestly don't know how to manage the lab. Sure; Abby's written some stuff down, but not much. On top of that, critical equipment, like her Master Mass Spec, has been damaged, I can't…"

Now Gibbs was in his face, so close that Tim could smell the coffee on his breath. "You what, McGee?"

Tim lowered his eyes. "I, uh, probably can't work as fast as Abby, but I'll try."

"Good," Gibbs said, with a smile, although it had no warmth. "See that you do."

* * *

Tim spent most of the morning figuring out what equipment still worked (only the most obvious casualties had been moved away from their moorings) and, in some cases, how it worked. There were a few small machines whose use was unknown to him. He'd never seen Abby use them, and had never thought to ask. Abby was always so frenetic in her lab that there never was time for such things.

Ziva came down to the lab in the early afternoon. Her smile was teasing. "Would you like me to bring your nameplate from your desk down here, McGee?"

"No, that's okay. The glass doors are supposed to be replaced tomorrow; I'll have the installers paint my name on those," he said with a grimace.

She looked around. "It seems darker in here now. With the street windows blown out, too, and boarded up, you are not getting daylight."

"Gibbs thinks I don't deserve daylight, anyway," Tim remarked. "I think he would wait if he could to get new windows and doors put in."

"I am sure it is not as bad as all that, McGee…then again, I did hear him say that he did not want to see you in the squad room." She patted his arm. "But anyway, I came here to deliver evidence from our newest case."

"You have a case?" Now Tim felt out of the loop. "When? Today? What was it about?"

"Dead Marine sergeant found in Rock Creek Park. He died of a stab wound. These flakes were found near the body." She handed him an evidence bag. "Gibbs says you are to figure out what they are, and how they relate to the crime."

He was stunned, as reality set in. "But I'm not Abby…"

"Oh, just ask yourself what Abby would do, and then turn up your music loud and it will all fall in place for you."

She left him then, as he winced at thinking it could be so easy.

* * *

The work was difficult…tedious, and with no ready answers. If he'd been given an assignment like _determine whose fingerprints are on this, McGee_, it would have gone much easier. Fingerprints, he knew how to do. Now he was reaching into his mind to retrieve brain cells that hadn't been used in about ten years to determine which forensic steps he should be taking.

"What'cha got, Abbs?"

Tim jumped at the sound of the gruff voice, and then saw it was Tony doing a Gibbs imitation. Tony snickered. "Had you there for a moment, didn't I? Here; have a_ Caf-Pow!_"

"What do you _want_, Tony?" Tim said in exasperation.

"The bossman wants to know about those flecks we brought back. Don't you have results yet? Abby would—"

_"I'm not Abby,"_ Tim growled. "Look; I have a degree related to this work, but I've never really done much of it. Given time, I could figure it out but…why don't you lend a hand? I'll show you the slide I made, and you can look in that microscope, and—"

"And nothing. I wasn't hired to peep into geek equipment."

Tim hesitated before a thought came to him. "I could tell Gibbs I need an assistant. I could specifically request you."

Tony shot him a look. "You wouldn't do that…You would. All right, Mr. Science Guy; bring on your slide."

"Paint flecks," Tim said blandly, when Gibbs himself came down a little while later. That's what Tony had proclaimed them to be, confirming Tim's suspicion, and that had given Tim the courage to make further tests. "Epoxy paint chips."

Gibbs looked a little surprised. "They didn't come off a car or truck?"

"Nope. No trace of rust or dirt, other than the surrounding soil. No signs of chemical aging. Looks at the harmonious colors: light blue, dark blue, gray. This was meant to liven up something dull, like in painting a concrete floor. The colors mix in with the paint."

"How would it be spilled there in the woods?"

"Well, I checked with Ducky, boss, and he said some of the flakes were found in the sergeant's pocket. The photos of the crime scene show that these chips were found near his hand…his right hand, and Ducky says he was right-handed. He scattered those before he died to provide a clue."

Gibbs appeared to be almost impressed. "Thought Master Mass Spec was broken."

"It is. Boss, we don't always need the latest equipment to solve crimes."

For that, Tim got a glare, and he wondered if he'd gone too far. Gibbs left without further ado.

* * *

Over the next several days, Tim got numerous puzzles to solve…and he did begin to think of them as puzzles, which made it all the more intriguing. He donned the red lab worker's jump suit more than once to crawl in, over or under a vehicle. He quickly learned, after getting two shirts stained, why Abby usually wore a lab coat.

One thing he realized he was doing differently than she did was to rely more heavily on the internet. He didn't have the same training that she did, but he knew where to start looking for answers. In addition, he had a network of college professors and acquaintances that he could turn to with questions, and he did. _What does this chemical coating look like after a month in a dry heat environment? Are there other ways of matching striations? To determine the velocity of this type of projectile…_ When a replacement for Master Mass Spec arrived, a week after Tim's assignment to the lab, Tim hardly gave it a second glance. _Let Abby break it in. I don't need it!_

His results were slow in coming, but they were correct. Because he was methodical, he was sure of his answers when he presented them. Gibbs, though, would only grunt. Tim knew he was still in the doghouse for having, in Gibbs' eyes, caused the accident that had wounded Gibbs' favorite.

* * *

Then, about three weeks in, there came a puzzle that he couldn't solve. He appealed to Jimmy, to Ducky, to Ziva, to Tony all for fresh eyes on the case. It was a complicated radiation problem, outside any of his fields of expertise. Hours of online research failed to yield anything. Calls to acquaintances would be useless without divulging information that likely should be classified. When Gibbs came down for a progress report, Tim wouldn't meet his eyes.

"Well, McGee?"

"I don't know, boss," Tim said, barely above a whisper. "I'm stumped. I don't know where to go to find the answer. I can never be Abby. You can…put a reprimand in my file if you want to. I didn't realize it would be so…hard."

"McGee. Look at me."

Tim turned defeated eyes on him, wondering what was to come.

"You think Abby has always come up with a solution? There are at least half a dozen times I can name when she's been stumped, too. Not as much now as before, but boy, does it irritate her when it happens. So you struck out. We'll get by."

Unbelievable relief flooded over Tim. "Thank you, boss," he said, looking away and touching his still-sore ribs. "You know," he said slowly, "in free moments here I've been recreating the…the explosion we had here. I've, uh, come to a conclusion."

"Well?"

"Uh, I was right the first time. I didn't cause it. Abby was mixing chemicals, and from what I can tell, there must have been a spark, and…I'm sorry, boss! I know it's not what you wanted to hear. But it was Abby's fault, indirectly, if nothing else."

"I know."

"What—? You _know_? How?"

Gibbs sat down on a stool. "She told me. About a week after the accident. She remembered exactly what she did, and said she felt at the time that she probably shouldn't be doing the mixing so close to s heat source."

Tim almost fell over. He flapped his arms. "You—you _knew_, and yet you accused _me_ of—"

"Settle down. I didn't know at first."

"But why—?"

"I wanted to see how you would do. You started out stumbling in here, but then you gained confidence and did pretty well. I needed someone to fill in for Abby. Ziva couldn't do it. Tony couldn't do it. Palmer might, but not full-time, and not as well. I thought you could, and you've proven me right. You tried something unfamiliar, and you didn't complain much. You just jumped in and went to work." He extended a hand to shake. "Thank you, Tim."

It still riled Tim a little that Gibbs hadn't revealed the truth when he knew it, but it didn't bother Tim much. "Thanks, boss. Can I have my old job back?"

Gibbs laughed and gave him a pat on the back. "In two weeks, when Abby comes back. You should be cleared for a return to the field by then. In the meantime…"

"What?"

"Can you come upstairs when you get a chance? Tony broke the clicker for the plasma. Maybe you can fix it."

Tim grinned. "After the experience here…I'll try anything."

-END-


End file.
